I just wanted to add to this, as I also understand where you're coming from. I'm now 35 weeks pregnant with a boy. The reason I found out was because I knew that I really wanted - even expected - a girl.
Someone earlier in the thread suggested that you do try to find out the sex of your baby, and given how strongly you feel on this issue, I do think this should be up to you rather than your husband to decide - talk to him and I'm sure he'll understand. Far easier to handle now, and seek the help you need so that when the time comes you are able to welcome your little boy whole-heartedly. For one, you may find you're having a little girl, in which case you can relax and enjoy the pregnancy, putting all this behind you!
If you find it's a boy, then you can start to manage your expectations and focus instead on the little individual character that you'll be greeting rather than his sex. Whilst you may not have the same experience as me, this is my journey:
I felt very upset after the 20 week scan when the gender was confirmed. And having had a miscarriage last year I felt horribly ungrateful, and the guilt just compounded all the other negative feelings. (But I think it goes to prove that the emotions come from completely separate places - you're not 'wrong' or a bad person to feel it.)
Over the last few months, I've raised the subject of gender preference with people - friends and family mostly, but I'm sure professional help is out there if you need it. I didn't make too big a deal of it, but wanted the reassurance that I wasn't alone - exactly as you've done here, and have proven that you're not!
But then I also sat down to think about exactly what was at the root of these feelings. Breaking it down like this enabled me to rationalise the emotions, and that really helped. The reasons were quite complex and often subconscious - to do with expectations of others, limited and negative experiences of men, even my own self-perception as a girlie person.
To get to this level of understanding has taken time as well as the support of others so I really do hope you don't give up cherryberry. It certainly isn't easy to handle criticism, especially when you're feeling fragile, so it's brave to raise a subject like this - but you did the right thing. Focus on the comments that make you feel stronger. Like all 'advice' - it's offered freely, and you take what you need from it. (But like others, I think SOH said it all so well.)
Now that I'm close to the birth, I feel much more adjusted to the idea of being mother to a boy and am looking forward to meeting him. I do hope that however you handle it, and whatever the outcome you feel better in the end, and I'm sure you'll absolutely love the new little person in your life.
xx